1. Field of the Invention
The invention relates generally to metallurgical vessels containing molten metallic material, the vessels being of the type provided with a gas inlet at substantially the bottom-most portion thereof; the gas inlets provided are usually necessary to admit a particular gas, e.g., oxygen or air, to aid in the metallurgical process which the molten material in the vessel is required to undergo.
The invention teaches an arrangement of a gas inlet blow pipe containing at least one gas permeable refractory insert, in the wall of a melt-containing vessel, for the introduction of gases in the vessel. The gas permeable inserts are inserted in a metallic or ceramic gas inlet blow pipe which is disposed in a slidable fashion in the vessel wall.
2. Description of Prior Art
Before the advent of more recent technology, it was common practice to block or plug the gas inlet by means of a clay plug or a plug of ceramic material which is compatible with the encountered temperature in the metallurgical vessel, and the reaction which takes place therein. Whenever the need to open the gas inlet arose, the plugs were drilled open so as to enable the connection of say, a gas lance. More recently, to avoid the inconvenience and the delay caused by having to drill out the plug holes, metallic or ceramic blast pipes passing through the vessel wall have been used.
A prior art arrangement of a gas pipe inlet in a metallurgical vessel is known from German Patent Publication DE-OS No. 30 03 884. This known arrangement has certain disadvantages in that because the refractory inserts in the pipe are relatively hard, the task of boring out, for purposes of replacement of especially the innermost insert, which may have been rendered unusable after stoppage of gas flow, is time consuming. In addition to the wear of the refractory lining of the vessel wall in the area of the blast pipe, the front end of the gas inlet pipe containing the insert is also subject to wear. The maintenance of the refractory lining following wear usually comprises pouring in suitable materials by the so-called process of slag coating; in such process, additional measures must be taken to renew the operating condition of the gas inlet installation, since the blast pipe and the innermost insert undergo a gradual setback with respect to and because of the erosion of their original length. Hitherto, this problem could only be solved by boring out the worn front end of the gas flushing pipe and inserting a new gas flushing pipe insert.
The U.S. equivalent of the German Patent Publication DE-OS No. 30 03 884 is U.S. Pat. No. 4,331,471 to Langenfeld et al, issued on May 25, 1982. The Langenfeld patent is assigned to the same assignee as the present invention and is incorporated herein by reference.